Stents are commonly placed inside blood vessels in order to widen narrowed or occluded blood vessels and, subsequently, to ensure that the blood vessel remains widened. Heating a stent subsequent to its implantation has been shown to prevent restenosis of the blood vessel (i.e., the re-narrowing of a blood vessel after it has been widened).
When a solid material is heated until its melting point, the material undergoes a phase-change to its liquid state. During the phase-change, the material accumulates a certain amount of heat, which is called the latent heat of fusion, or the enthalpy change of fusion. The temperature of the material stays relatively constant when the phase change occurs. When the process is reversed, i.e., when the material undergoes a phase-change from liquid to solid, the accumulated latent heat is released.
In oncology, the Warburg effect describes the observation that most cancer cells predominantly produce energy by glycolysis followed by lactic acid fermentation, rather than by oxidation of pyruvate like most healthy cells. The Warburg effect results in cancer cells consuming more than 20 times the quantity of glucose to produce energy than do healthy cells, ceteris paribus.
An article on Wikipedia (18 Jan. 2009) entitled “Fluorodeoxyglucose” states “FDG [Fluorodeoxyglucose] is most commonly used in the medical imaging modality positron emission tomography (PET): the fluorine in the FDG molecule is chosen to be the positron-emitting radioactive isotope fluorine-18, to produce 18F-FDG. After FDG is injected into a patient, a PET scanner can form images of the distribution of FDG around the body. The images can be assessed by a nuclear medicine physician or radiologist to provide diagnoses of various medical conditions . . . FDG, as a glucose analog, is taken up by high-glucose-using cells such as brain, kidney, and cancer cells, where phosphorylation prevents the glucose from being released intact. The 2-oxygen in glucose is needed for further glycolysis, so that (in common with 2-deoxy-D-glucose) FDG cannot be further metabolized in cells, and therefore the FDG-6-phosphate formed does not undergo glycolysis before radioactive decay. As a result, the distribution of 18F-FDG is a good reflection of the distribution of glucose uptake and phosphorylation by cells in the body.”
A shape-memory alloy is an alloy, such as nitinol or copper-aluminum-nickel, that has a first shape when it is below a given temperature (the “transformation temperature”), and that changes to assume a second shape when it is heated to the transformation temperature.
PCT Publication WO 94/001165 to Gross describes a medication administering device includes a housing introducible into a body cavity and of a material insoluble in the body cavity fluids, but formed with an opening covered by a material which is soluble in body cavity fluids. A diaphragm divides the interior of the housing into a medication chamber including the opening, and a control chamber. An electrolytic cell in the control chamber generates a gas when electrical current is passed therethrough to deliver medication from the medication chamber through the opening into the body cavity at a rate controlled by the electrical current. The device can be in the form of a pill or capsule to be taken orally.
US Patent Application Publication 2006/0241747 to Shaoulian describes tissue shaping methods and devices. The devices are described as being adjusted within the body of a patient in a less invasive or non-invasive manner, such as by applying energy percutaneously or external to the patient's body. In one example, the device is positioned within the coronary sinus of the patient so as to effect changes in at least one dimension of the mitral valve annulus. The device is described as including a shape memory material that is responsive to changes in temperature and/or exposure to a magnetic field. In one example, the shape memory material is responsive to energy, such as electromagnetic or acoustic energy, applied from an energy source located outside the coronary sinus. A material having enhanced absorption characteristics with respect to the desired heating energy is also described as being used to facilitate heating and adjustment of the tissue shaping device.
U.S. patent application Publication 5,545,210 to Hess describes a permanent tissue supporting device, and a method for supporting tissue, wherein a stent-like member comprising a shape-memory alloy is permanently positioned to support the tissue of a tubular organ of a living body. The shape-memory alloy of the positioned stent-like member is in the martensitic state and exhibits a strain on a horizontal plateau of a stress-strain curve of the shape-memory alloy when permanently positioned in the tubular organ.
U.S. Pat. No. 6,059,810 to Brown describes a stent for reinforcing a vessel wall, the stent being expandable and comprised of a shape memory alloy which in the normal implanted condition is in the martensitic phase at body temperature, the stent further having a larger parent or austenitic shape and diameter when heated above its transition temperature.
Galil Medical (Yokneam, Israel) manufactures cryotherapy systems.
The following references may be of interest:
U.S. Pat. No. 6,805,711 to Quijano
U.S. Pat. No. 6,451,044 to Naghavi et al.
U.S. Pat. No. 6,323,459 to Maynard
U.S. Pat. No. 6,120,534 to Ruiz
U.S. Pat. No. 5,964,744 to Balbierz
U.S. Pat. No. 5,830,179 to Mikus
U.S. Pat. No. 5,716,410 to Wang
U.S. Pat. No. 5,667,522 to Flomenblit
US Patent Application Publication 2002/0183829 to Doscher et al.
US Patent Application Publication 2004/0253304 to Gross
US Patent Application Publication 2004/0180086 to Ramtoola
United States Patent Application Publication 2005/0055082 to Ben Muvhar
US Patent Application Publication 2005/0288777 to Rhee
US Patent Application Publication 2006/0074479 to Bailey
US Patent Application Publication 2006/0241747 to Shaoulian et al.
US Patent Application Publication 2008/021537 to Ben Muvhar
PCT Publication WO 02/000145 to Diamantopoulos
PCT Publication WO 03/028522 to Ben Muvhar
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“The next generation of cancer treatments may be delivered by nanoparticles,” The Economist, Nov. 6, 2008
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